Engine Won't Start After Compression Test
- Thread starter MonkeyCam
- Start date
I've tried to start it w/ the choke both opened & closed. Doesn't make a difference.
Somebody somewhere must know what the problem is. If I can't get an answer on a small-engine forum of all places, then that's pretty surprising, & I guess I'll have to start shopping for a new mower (or at least a new engine) to replace the 2-yr.-old, well-maintained one that suddenly & inexplicably crapped out.
I've got compression, fuel, & spark, so what's the problem??? :confused2:
primerbulb120
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1. Take off the muffler and try to start the mower without it. If the mower starts, the muffler is clogged.
2. If the muffler is not clogged, try replacing the spark plug. Inline spark tester will not tell you if you have a shorted spark plug, try a new one and see if it helps.
2. If the muffler is not clogged, try replacing the spark plug. Inline spark tester will not tell you if you have a shorted spark plug, try a new one and see if it helps.
Bought & installed a new spark plug & removed the muffler. Still won't start.
I can't help but think that this problem was brought on by the compression test I did; everything was fine until then . . . or else it's just a very misleading coincidence, which I have a hard time believing.
I can't believe that a mower I bought new, took good care of, & used for only 2 seasons is on the verge of needing to be replaced b/c it mysteriously & stubbornly refuses to start after a simple compression test. What the hell?!?!
:confused2:I feel we are overlooking something simple. I am wondering if you are actually getting spark under compression. There was an issue with some of the XT engines a few years ago where the the tab the brake cable connects to would flex over time and hit a point were it would release the flywheel brake but not enough to get a reliable spark.
Maybe disconnect the kill wire from the module and see what happens.
Maybe disconnect the kill wire from the module and see what happens.
I removed the blower housing & saw that the brake pad fully disengaged from the flywheel when the lever was held against the handle.
But your comment reminded me of something I noticed earlier today: with the spark plug removed, the starting rope is nearly as hard to pull as when the spark plug is screwed in firmly. Shouldn't it be a lot easier instead? Could that be a clue?
Definitely something odd there. I may of missed it but what was the compression reading that you took. And if possible recheck it and see it it changed. I am wondering if something was going on at the end of your last mowing session, and is now come to light.
7394
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Yes, it should spin relatively freely with spark plug removed. That Compression tester ? Did the threaded hose end have longer threads than the spark threads ? I'm now wondering if it hit something in the combustion chamber ? You never posted any readings (or I missed them).
The compression reading after 6 pulls on the starting rope was 105, & I performed the test 2 or 3 times. And the screw-in nozzle on the compression tester doesn't reach as far into the chamber as the spark plug does.
BTW, thanks for the replies; I really appreciate it. :smile:
It's late, & I need to get to bed, but I'll do another comp. test tomorrow & post the result.
BTW, thanks for the replies; I really appreciate it. :smile:
It's late, & I need to get to bed, but I'll do another comp. test tomorrow & post the result.
cpurvis
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Just curious...why were you wanting to check the compression on a two year-old mower, well-maintained mower?
If it doesn't spin easily without a spark plug, that could mean that the blade brake is dragging. My daughter had a Craftsman mower with Briggs engine which incorporated the kill switch into the blade brake function. There was an arm on the left side of the engine that was pushed forward by the housing of the safety cable (dead man's switch). That cable became so stretched that it wouldn't push that arm forward enough to allow the engine to start. After I replaced that cable, the problem was fixed.
If it doesn't spin easily without a spark plug, that could mean that the blade brake is dragging. My daughter had a Craftsman mower with Briggs engine which incorporated the kill switch into the blade brake function. There was an arm on the left side of the engine that was pushed forward by the housing of the safety cable (dead man's switch). That cable became so stretched that it wouldn't push that arm forward enough to allow the engine to start. After I replaced that cable, the problem was fixed.